title: Indigenous microbes survive in situ ozonation improving biodegradation of dissolved organic matter in aged oil sands process-affected waters.
abstract: The oil sands industry faces significant challenges in developing effective remediation technologies for process-affected water stored in tailings ponds. Naphthenic acids, a complex mixture of cycloaliphatic carboxylic acids, have been of particular concern because they concentrate in tailings ponds and are a component of the acutely toxic fraction of process water. Ozone treatment has been demonstrated as an effective means of rapidly degrading naphthenic acids, reducing process water toxicity, and increasing its biodegradability following seeding with the endogenous process water bacteria. This study is the first to examine subsequent in situ biodegradation following ozone pretreatment. Two aged oil sands process-affected waters from experimental reclamation tailings ponds were ozonated to reduce the dissolved organic carbon, to which naphthenic acids contributed minimally (<1mgL(-1)). Treatment with an ozone dose of 50mgL(-1) improved the 84d biodegradability of remaining dissolved organic carbon during subsequent aerobic incubation (11-13mgL(-1) removed from aged process-affected waters versus 5mgL(-1) when not pretreated with ozone). The ozone-treated indigenous microbial communities were as capable of degrading organic matter as the same community not exposed to ozone. This supports ozonation coupled with biodegradation as an effective and feasible treatment option.
authors.affiliation: Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Lisa D
authors.initials: LD
authors.lastname: Brown
authors.forename: Leonidas
authors.initials: L
authors.lastname: Pérez-Estrada
authors.forename: Nan
authors.initials: N
authors.lastname: Wang
authors.forename: Mohamed Gamal
authors.initials: MG
authors.lastname: El-Din
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Martin
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Fedorak
authors.forename: Ania C
authors.initials: AC
authors.lastname: Ulrich
mesh_terms: D001673:Biodegradation, Environmental; D052918:Environmental Restoration and Remediation / Q000379:methods*; D007220:Industrial Waste / Q000032:analysis; D061329:Oil and Gas Fields; D010126:Ozone / Q000737:chemistry; D010578:Petroleum; D014865:Waste Disposal, Fluid; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity
chemical_list: D007220:Industrial Waste; D010578:Petroleum; D014874:Water Pollutants, Chemical; D010126:Ozone
keywords: Biodegradation; End-pit lakes; Naphthenic acids; Oil sands process-affected water; Organic matter; Ozone treatment